Choose a workshop that you're comfortable with....build up a rapport over time....don't keep skipping from one to another or playing one off against the other.....take advice from your chosen workshop.....if there is a good reason to get a job done elsewhere (eg your workshop is very busy or doesn't have the equipment needed) have the courtesy to inform them....all this leads to good relations and trust...and getting good advice....and getting the job done right.
This has been my experience with the same Subaru workshop I have used for the past 23 years (which is probably greater than the age of quite a few on this forum).

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No Subarus currently owned